x/2(x+1),1/x^2-x通分
问题描述：
x/2(x+1),1/x^2-x通分
答
x/[2(x+1)]=x*x(x-1)/[2x(x+1)(x-1)]=x^2(x-1)/[2x(x+1)(x-1)]
1/(x^2-x)=1/[x(x-1)]=2(x+1)/[2x(x+1)(x-1)]